In a typical of digital broadcasting system, after the video data and audio data of plural channels are compression-coded using for example the MPEG2 (moving picture experts group phase 2) standard. The data is packetized per the predetermined unit (such as a 184 bit) (hereinafter, the resultant packets are referred to as TS (transport stream) packets) and multiplexed, to form a transport stream which is then transmitted via terrestrial wave, satellite wave or cable as the digital broadcasting signal.
In such digital broadcasting system, a receiving apparatus extracts TS packets corresponding to a desired channel from among the TS packets contained in the transport stream received as a digital broadcasting signal, and decodes them back to the video data and audio data in the original signal format according to the reverse procedure to the compression processing.
In recent years, such a receiving apparatus has a plurality of digital signal output terminals for external connections (hereinafter referred to as digital output terminal). This allows audio data obtained by the aforementioned decoding, after being converted into a predetermined format, to be output to an external apparatus via an IEC (International Electro-Technical Committee) 958 format optical digital audio output terminal or to be output to an external apparatus via a high-speed serial interface such as an IEEE (Institute of Electrical and Electronics Engineers) 1394, or allows the transport stream before decoding itself to be output to an external apparatus.
Since degradation in image quality and sound quality does not occur in digitized video data and audio data, a digital recording apparatus can duplicate digital data an unlimited number of times without degradation in quality.
Therefore, in general, by transmitting video data and audio data after adding predetermined copy control data (CCI: copy control information) at the transmitting end, copying is restricted based on the copy control data at the digital receiving end, and thus, unlawful copying can be prevented.
According to the SCMS (serial copy management system) adopted in the IEC 958 standard, this copy control data has three types of information: “never copy”, “copy once”, and “copy free”. More specifically, “never copy” indicates that copying is not allowed, “copy once” indicates that only one copy is allowed (after one copy the copy control data shifts to “never copy”), and “free copy” indicates that copying is allowed an unlimited number of times. In the aforementioned digital broadcasting system, such copy control data is added to each program.
However, in a digital broadcasting signal with copy control data, set to “copy once” is received by the aforementioned receiving apparatus and the receiver is connected to a plurality of digital recorders, the digital signal is output from each of the plurality of digital output terminals at the same time. Therefore, even if only one copy is allowed more than one copy may be made by connecting each digital output terminal to a digital recording apparatus.
In addition, in practice, it has been quite difficult for the receiving apparatus equipped with plural digital output terminals to use new application that limits the number of copies such as pay-per-download.